Rocks, kinds of Rocks, Rock Cycle

Rocks are made of one or more minerals.

Minerals are natural, inorganic solids. ( Inorganic = made from non-living materials which do not have carbon ) Each mineral is made of specific elements and has a specific crystal structure. A mineral may be one element such as copper (Cu) or gold (Au), or it may be a mixture of several elements. About 2,500 different minerals have been described.

Kinds of rocks: Igneous, Sedimentary, and Metamorphic.

Igneous Rocks

Igneous rocks are made from lava or magma. Lava and magma are made of hot, melted minerals. Lava is found on or near the Earth’s surface. Magma is found far beneath the Earth’s surface.

• Extrusive igneous rocks are made from lava that cooled quickly. Extrusive rocks generally have either no crystals or very tiny crystals. Intrusive igneous rocks are made from slow-cooling magma. Intrusive rocks have large crystals. pumice, basalt, obsidian, scoria, rhyolite, andesite
• Intrusive igneous rocks: granite, gabbro, diorite

Sedimentary Rocks

On Earth’s surface, wind, ice, and water can break rock into pieces. They can also carry rock pieces to another place. Usually, the rock pieces, called sediments, drop from the wind or water to make a layer. The layer can be buried under other layers of sediments. Sometimes, the sediments can even be made from seashells and bodies of plants and animals. Fossils are found in sedimentary rocks. After a long time the sediments can be cemented together to make sedimentary rock. In this way, igneous rock can become sedimentary rock.

• Detrital sedimentary rocks are made from broken pieces of other rocks. sandstone, shale, siltstone, conglomerate, coal
• Chemical sedimentary rocks. chemical limestone, halite
• Organic sedimentary rocks are made from the bodies of dead animals or plants. fossil-rich limestone, coquina, coal

Metamorphic Rocks

Metamorphic rocks are made from older rocks, either igneous or sedimentary. These rocks are changed by great heat and/or pressure deep beneath the earth’s surface. The heat and pressure makes crystals in the rock. If the rock already has crystals, the heat makes the crystals larger. Sometimes the pressure flattens the crystals into layers.

Rock Cycle

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Tags: kinds of rocks, natural science, rock, rock cycle, Science, types of rocks

Category: Earth Science